Piston-ring.



T. DAVIS.

PISTON RING. APPLIGATION TILED JAN.13. 1311.

Patented 001;.3,1 911.

ring 15 plementa cape of the fluid pressure medium past the 30 any suitable t UNITED STATES OFFICE.

THOMAS DAVIS, OF IEITTSIB'l'IIBIG'H,- PENNSYLVANIA.

PISTON-RING.

Specification of Letters Patent.

Application filed January 13, 1911.

Serial No. 602,488.

To all whom it may concern:

Be it known that I, THOMAS DAVIS, a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Piston-Rings, of which the following is a specification.

Thls invention relates to plstons for fluid pressure 0 hnders, and more partlcularly to the pae ing rings therefor.

Theobject of the invention is to provide a piston and ring construction whereby the left by the pint or split of the expans1 e device, so as to prevent the espiston.

The invention comprises the construction and arrangement of parts hereinafter described an claimed. In the accompanying drawing Figure 1 is a Ion 'tudinal section through a cylinder rovi ed with my improved piston; Fig. 2 IS a view of the piston head with the remov- 26 able plate and expansible ring omitted; Fig.

3 is a similar view ,with merely the removable plate omitted; and Fig. 4 is a perspectiveview of the removable plate.

In the" drawings 1 indicatesa-cylinder of 8, form and size, which may used either or steam, com ressed air, gas under pressure, or water. e inlets and outlets of the cylinder are not indicated, as they form no part of the invention. The

,istoncomprises a head 2 provided with a 11b 3 and: provided with an axial opening for receiving the threaded extension 4 of pistonrrod 5. The latter extends through an opening in head 6 of the cylinder, and if 40, not connected to a cross-head or the like is prevented from rotary movement by being rovided with a keyway 7 which is enga e a projection 8 on the cylinder hea 6.

T he head 2 also is prevented from rotary: 46 movement relative to the iston stem by means of a screw 9 tap ed through a radial hole in the hub 3 and entering a slot or groove 10 in the threaded GXtBD'SIOHA: of the piston rod. The face of the piston opposite the head 2 is formed by a plate 11 which is 'Icmovably secured to the head and piston stem by means of nut 12 on the end of the threaded extension of said stem.

Between the removable plate 11 and head '65 2 .is the packing ring and supplemental meme 1 e Pwkmg g issho'wn at .14,

is closed or obstructed by a supand this may be of methhbrsdftnnaterial such as rubber or the like. 'Thisjring is split" on one side, as at 15, sdfthatiitis expand. It may be expafidd'byj able spring or s rings, the rawitigs showing-a. plurality -0 short plate springs.- ftfi betwemi the ex 7 ansible .ring ring 1 located within t he packing i-i'n When the packing ring is of'iseftfina teria such as lead or rubber, tsinnerface preferably reinforced by a metal ring ls ito prevent the springs 16 from cuttin Into the soft packing. This metal 1 likewise is split so that it easily, e'XpandsunderQthe action of springs 16. Asfthe packing ring Patented Octi 191:1.

1 a d af continudus wears it will have to expanamore and more,

thereby opening to a la sr'aegree the 'g ap at 15. To prevent the fluid :pressureginedium from escaping throifghlsuc'h gapIjpr ovide a supplemental device which comprises a circular ring or plate 20 located"between the packing ring and the head 2. This plate or ring 20 has a ground fit with'the face of the head 2, so that fluid ressuiecannht escape between the two. t L loosely 'Qsufrrounds the hub 3 of thelpistoii'hea'dandfis merely pressed radially toward the hylinder walls in the direction of -the locationof the gap or split 15 in the packing riiiQ'Any suitable spring arrangement can "used 'for this purpose. I have shown a flatsprin' g21 bearing against the hub B of "the piston head and having its ends engaging shoulders 22 on the ring or' plate 20, This spring is arranged to ress the ringorplate; 20' in the direction 0? the arrow '23,shown,dnFig'l 3,

and against the wall of thecyliiideratthe point where the gap 15- infthe paeking'ifing occurs. Consequently the plate' O {ones a supplemental packing and closure-war such mg through the latter?"- To insure the plat-e2 0 being at? an titties ressed in the directiori iii'which tl'rejghpd5 is located, the parts in'ust be .hld---against ap andprev'ents fluid pressiire A v the ring ag means for normally holding all of the parts of extending into the gap 15 between the ends of the packing ring. By this arrangement the piston are held in proper relative positions thereb insuring the spring 21 always pressing t e supplemental plate or rin 20 in the direction occupied by the gap etween the ends of the packing ring.

To counterbalance the action of spring 21 I provide a bowed spring 30 located diametrically; opposite spring 21 and having its ends caring against t 1e inner face of ring 16 and intermediate its ends bearing against the hub 3 of the piston head. Holes 32 and 33 are preferably made in plate 11 to permit the pressure fluid to enter between the plate and the head and assist in expandin the packing ring and also to force it and ainst the head 2.

The operation of the parts described will be clearly understood from the foregoing description in connection with the drawings. The arrangement illustrated and described provides a perfect packing for the piston and enables the use of a ackmg ring formed of any desired materia and absolutely prevents the fluid pressure medium from ascaping through the joint which necessariiy is formed in all expansible packing rings. What I claim is:

1. In a piston, the combination of a piston head, a split packing ring, a'supplemental packing member having a tightfit between said packing ring and said head and movable radially to the axis of the pis ton, said packing ring and supplemental" packing member being provided with fiat sidefaces bearing against each other, and

said supplemental member a ainst the cylinder on the side where the spit in the packing ring is located.

2. In a piston, the combination of a piston head, a split packing ring, a circular member having a tightfit between said ring and said head and movable radially to the piston, men for normally holding said circular member against the cylinder walls on the side Where the split in the piston ring is located, and means for preventing relative rotation between the packing ring and said circular member.

3. In a piston, the combination of a piston head provided with a hub, asplit packin ring, a supplemental member having a tig t fit between said packing ring and said head, a s ring arranged between said supplementa member and the hub of the piston head and normally pressing said su plemental member against the cylmder we 1 on the side where the split in the packing ring is located, and a counterbalancing spring arranged diametrically opposite said first named spring and bearin respectively on, the hub of the piston hea and against the packing ring.

a. In a piston, the combination of a piston head, a face plate secured to the piston head, a split. packing ring, a supplemental packing member, said packing ring and supplemental packing member'bein located between the'piston head and said face plate, means for normally pressing said supplemental packing member toward the cylinder wall on the side where the split in the ack ing ring is located, and means for .110 ding all oifsaid parts a ainst relative rotation.

5. In a piston, t e combination of a pistonhead, a face plate secured thereto, a pair of packing members having cooperating flat side faces bearing tightly together, said packing members located between said head and face plate, and springs arranged to press said packing members in diametrically 0pposite directions.

6. In a piston, the combination of a piston head, a piston rod, a split packing ring in the pistonhead, a supplemental packing member in said head means for pressing the latter against the cylinder walls on the side where the split in thepacking ring is located, said packing-ring and supplemental packing member lying in diiferent planes transverse to the axisof the piston head and contacting faces, means for preventing rotation of the cylinder head on the piston rod, and means for preventing rotation of said split packing ring and said supplemental packing member relative to said head.

In testimony whereof I have hereunto set my hand.

THOMAS DAVIS. Witnesses:

Isaac E. l.\'ICCRACKEN, I. MCGLASHAN. 

